// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Atheros Communication Bluetooth HCIATH3K UART protocol
 *
 *  HCIATH3K (HCI Atheros AR300x Protocol) is a Atheros Communication's
 *  power management protocol extension to H4 to support AR300x Bluetooth Chip.
 *
 *  Copyright (c) 2009-2010 Atheros Communications Inc.
 *
 *  Acknowledgements:
 *  This file is based on hci_h4.c, which was written
 *  by Maxim Krasnyansky and Marcel Holtmann.
 */

#include <linux/module.h>
#include <linux/kernel.h>

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/skbuff.h>

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>

#include "hci_uart.h"

struct ath_struct {
        struct hci_uart *hu;
        unsigned int cur_sleep;

        struct sk_buff *rx_skb;
        struct sk_buff_head txq;
        struct work_struct ctxtsw;
};

#define OP_WRITE_TAG    0x01

#define INDEX_BDADDR    0x01

struct ath_vendor_cmd {
        __u8 opcode;
        __le16 index;
        __u8 len;
        __u8 data[251];
} __packed;

static int ath_wakeup_ar3k(struct tty_struct *tty)
{
        int status = tty->driver->ops->tiocmget(tty);

        if (status & TIOCM_CTS)
                return status;

        /* Clear RTS first */
        tty->driver->ops->tiocmget(tty);
        tty->driver->ops->tiocmset(tty, 0x00, TIOCM_RTS);
        msleep(20);

        /* Set RTS, wake up board */
        tty->driver->ops->tiocmget(tty);
        tty->driver->ops->tiocmset(tty, TIOCM_RTS, 0x00);
        msleep(20);

        status = tty->driver->ops->tiocmget(tty);
        return status;
}

static void ath_hci_uart_work(struct work_struct *work)
{
        int status;
        struct ath_struct *ath;
        struct hci_uart *hu;
        struct tty_struct *tty;

        ath = container_of(work, struct ath_struct, ctxtsw);

        hu = ath->hu;
        tty = hu->tty;

        /* verify and wake up controller */
        if (ath->cur_sleep) {
                status = ath_wakeup_ar3k(tty);
                if (!(status & TIOCM_CTS))
                        return;
        }

        /* Ready to send Data */
        clear_bit(HCI_UART_SENDING, &hu->tx_state);
        hci_uart_tx_wakeup(hu);
}

static int ath_open(struct hci_uart *hu)
{
        struct ath_struct *ath;

        BT_DBG("hu %p", hu);

        if (!hci_uart_has_flow_control(hu))
                return -EOPNOTSUPP;

        ath = kzalloc(sizeof(*ath), GFP_KERNEL);
        if (!ath)
                return -ENOMEM;

        skb_queue_head_init(&ath->txq);

        hu->priv = ath;
        ath->hu = hu;

        INIT_WORK(&ath->ctxtsw, ath_hci_uart_work);

        return 0;
}

static int ath_close(struct hci_uart *hu)
{
        struct ath_struct *ath = hu->priv;

        BT_DBG("hu %p", hu);

        skb_queue_purge(&ath->txq);

        kfree_skb(ath->rx_skb);

        cancel_work_sync(&ath->ctxtsw);

        hu->priv = NULL;
        kfree(ath);

        return 0;
}

static int ath_flush(struct hci_uart *hu)
{
        struct ath_struct *ath = hu->priv;

        BT_DBG("hu %p", hu);

        skb_queue_purge(&ath->txq);

        return 0;
}

static int ath_vendor_cmd(struct hci_dev *hdev, uint8_t opcode, uint16_t index,
                          const void *data, size_t dlen)
{
        struct sk_buff *skb;
        struct ath_vendor_cmd cmd;

        if (dlen > sizeof(cmd.data))
                return -EINVAL;

        cmd.opcode = opcode;
        cmd.index = cpu_to_le16(index);
        cmd.len = dlen;
        memcpy(cmd.data, data, dlen);

        skb = __hci_cmd_sync(hdev, 0xfc0b, dlen + 4, &cmd, HCI_INIT_TIMEOUT);
        if (IS_ERR(skb))
                return PTR_ERR(skb);
        kfree_skb(skb);

        return 0;
}

static int ath_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr)
{
        return ath_vendor_cmd(hdev, OP_WRITE_TAG, INDEX_BDADDR, bdaddr,
                              sizeof(*bdaddr));
}

static int ath_setup(struct hci_uart *hu)
{
        BT_DBG("hu %p", hu);

        hu->hdev->set_bdaddr = ath_set_bdaddr;

        return 0;
}

static const struct h4_recv_pkt ath_recv_pkts[] = {
        { H4_RECV_ACL,   .recv = hci_recv_frame },
        { H4_RECV_SCO,   .recv = hci_recv_frame },
        { H4_RECV_EVENT, .recv = hci_recv_frame },
};

static int ath_recv(struct hci_uart *hu, const void *data, int count)
{
        struct ath_struct *ath = hu->priv;

        ath->rx_skb = h4_recv_buf(hu->hdev, ath->rx_skb, data, count,
                                  ath_recv_pkts, ARRAY_SIZE(ath_recv_pkts));
        if (IS_ERR(ath->rx_skb)) {
                int err = PTR_ERR(ath->rx_skb);
                bt_dev_err(hu->hdev, "Frame reassembly failed (%d)", err);
                ath->rx_skb = NULL;
                return err;
        }

        return count;
}

#define HCI_OP_ATH_SLEEP 0xFC04

static int ath_enqueue(struct hci_uart *hu, struct sk_buff *skb)
{
        struct ath_struct *ath = hu->priv;

        if (hci_skb_pkt_type(skb) == HCI_SCODATA_PKT) {
                kfree_skb(skb);
                return 0;
        }

        /* Update power management enable flag with parameters of
         * HCI sleep enable vendor specific HCI command.
         */
        if (hci_skb_pkt_type(skb) == HCI_COMMAND_PKT) {
                struct hci_command_hdr *hdr = (void *)skb->data;

                if (__le16_to_cpu(hdr->opcode) == HCI_OP_ATH_SLEEP)
                        ath->cur_sleep = skb->data[HCI_COMMAND_HDR_SIZE];
        }

        BT_DBG("hu %p skb %p", hu, skb);

        /* Prepend skb with frame type */
        memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);

        skb_queue_tail(&ath->txq, skb);
        set_bit(HCI_UART_SENDING, &hu->tx_state);

        schedule_work(&ath->ctxtsw);

        return 0;
}

static struct sk_buff *ath_dequeue(struct hci_uart *hu)
{
        struct ath_struct *ath = hu->priv;

        return skb_dequeue(&ath->txq);
}

static const struct hci_uart_proto athp = {
        .id             = HCI_UART_ATH3K,
        .name           = "ATH3K",
        .manufacturer   = 69,
        .open           = ath_open,
        .close          = ath_close,
        .flush          = ath_flush,
        .setup          = ath_setup,
        .recv           = ath_recv,
        .enqueue        = ath_enqueue,
        .dequeue        = ath_dequeue,
};

int __init ath_init(void)
{
        return hci_uart_register_proto(&athp);
}

int __exit ath_deinit(void)
{
        return hci_uart_unregister_proto(&athp);
}